aeroplanes and dirigibles of war- 第31部分

earth；　and　the　higher　the　altitude　it　attains　the　greater　is　its

degree　of　safety。　　The　limit　of　ascension　is　governed　merely　by

the　physical　capacities　of　those　who　are　responsible　for　the

aerial　vessel's　movement。



It　is　for　this　reason　that　the　defensive　measures　which　are

practised　in　the　waters　of　the　earth　are　inapplicable　to　the

atmosphere。　　Movement　by；　or　in；　water　is　governed　by　the　depth

of　channels；　and　these　may　be　rendered　impassable　or　dangerous　to

negotiate　by　the　planting　of　mines。　　A　passing　ship　or　submarine

may　circumvent　these　explosive　obstructions；　but　such　a

successful　manoeuvre　is　generally　a　matter　of　good　luck。　　So　far

as　submarines　are　concerned　the　fact　must　not　be　over　looked　that

movements　in　the　sea　are　carried　out　under　blind　conditions：　the

navigator　is　unable　to　see　where　he　is　going；　the　optic　faculty

is　rendered　nugatory。　　Contrast　the　disability　of　the　submarine

with　the　privileges　of　its　consort　in　the　air。　　The　latter　is

able　to　profit　from　vision。　　The　aerial　navigator　is　able　to　see

every　inch　of　his　way；　at　least　during　daylight。　　When　darkness

falls　he　is　condemned　to　the　same　helplessness　as　his　confrere　in

the　waters　below。



A　well…known　British　authority　upon　aviation　suggested　that

advantage　should　be　taken　of　this　disability；　and　that　the　air

should　be　mined　during　periods　of　darkness　and　fog　to　secure

protection　against　aerial　invasion。　　At　first　sight　the　proposal

appears　to　be　absolutely　grotesque；　but　a　little　reflection　will

suffice　to　demonstrate　its　possibilities　when　the　area　to　be

defended　is　comparatively　limited。　　The　suggestion　merely

proposes　to　profit　from　one　defect　of　the　dirigible。　　The　latter；

when　bent　upon　a　daring　expedition；　naturally　prefers　to　make　a

bee…line　towards　its　objective：　fuel　considerations　as　a　matter

of　fact　compel　it　to　do　so。　　Consequently　it　is　possible；　within

certain　limits；　to　anticipate　the　route　which　an　invading　craft　

will　follow：　the　course　is　practically　as　obvious　as　if　the

vessel　were　condemned　to　a　narrow　lane　marked　out　by　sign…posts。

Moreover；　if　approaching　under　cover　of　night　or　during　thick

weather；　it　will　metaphorically　〃hug　the　ground。〃　To　attempt　to　

complete　its　task　at　a　great　height　is　to　court　failure；　as　the

range　of　vision　is　necessarily　so　limited。



Under　these　circumstances　the　mining　of　the　air　could　be　carried

out　upon　the　obvious　approaches　to　a　threatened　area。　　The　mines；

comprising　large　charges　of　high…explosive　and　combustible

material；　would　be　attached　to　small　captive　balloons　similar　to

the　〃sounding　balloons〃　which　are　so　much　used　by　meteorologists

in　operations　for　sounding　the　upper　strata　of　the　atmosphere。　　

These　pilot　balloons　would　be　captive；　their　thin　wires　being

wound　upon　winches　planted　at　close　intervals　along　the

coast…line。　　The　balloon…mines　themselves　would　be　sent　to

varying　heights；　ranging　from　1；000　to　5；000　feet；　and　with

several　attached　to　each　cable；　the　disposition　of　the　mines

in　the　air　in　such　an　irregular　manner　being　in　fact　closely

similar　to　the　practice　adopted　in　the　mining　of　a　channel　for

protection　against　submarines　and　hostile　ships。



The　suggestion　is　that　these　mines　should　be　sent　aloft　at　dusk

or　upon　the　approach　of　thick　and　foggy　weather；　and　should　be

wound　in　at　dawn　or　when　the　atmosphere　cleared；　inasmuch　as　in

fine　weather　the　floating　aerial　menace　would　be　readily　detected

by　the　pilot　of　a　dirigible；　and　would　be　carefully　avoided。　　If

the　network　were　sufficiently　intricate　it　would　not　be　easy　for

an　airship　travelling　at　night　or　in　foggy　weather　to　steer　clear

of　danger；　for　the　wires　holding　the　balloons　captive　would　be

difficult　to　distinguish。



The　mines　would　depend　upon　detonators　to　complete　their　work；

and　here　again　they　would　bear　a　close　resemblance　to　sea…mines。

By　looping　the　mines　their　deadliness　could　be　increased。　　The

unsuspicious　airship；　advancing　under　cover　of　darkness　or　thick

weather；　might　foul　one　of　the　wires；　and；　driving　forward；　would

tend　to　pull　one　or　more　mines　against　itself。　　Under　the　force

of　the　impact；　no　matter　how　gentle；　or　slight；　one　or　more　of

the　detonating　levers　would　be　moved；　causing　the　mine　to

explode；　thus　bursting　the　lifting　bag　of　the　vessel；　and　firing

its　gaseous　contents。　　An　alternative　method；　especially　when　a

cable　carried　only　a　single　mine；　would　be　to　wind　in　the　captive

balloon　directly　the　wire　was　fouled　by　an　invading　aerial　craft；

the　process　being　continued　until　the　mine　was　brought　against

the　vessel　and　thereby　detonated。



Another　proposed　mining　method　differs　materially　in　its

application。　　In　this　instance　it　is　suggested　that　the　mines

should　be　sent　aloft；　but　should　not　be　of　the　contact　type；　and

should　not　be　fired　by　impact　detonators；　but　that　dependence

should　be　placed　rather　upon　the　disturbing　forces　of　a　severe

concussion　in　the　air。　　The　mines　would　be　floating　aoft；　and

the　advance　of　the　airship　would　be　detected。　　The　elevation

of　the　mines　in　the　vicinity　of　the　invading　craft　would　be

known；　while　the　altitude　of　the　airship　in　relation　thereto

could　be　calculated。　　Then；　it　is　proposed　that　a　mine　within　d

certain　radius　of　the　approaching　craft；　and；　of　course；　below

it；　should　be　fired　electrically　from　the　ground。　　It　is

maintained　that　if　the　charge　were　sufficiently　heavy　and　an

adequate　sheet　of　flame　were　produced　as　a　result　of　the

ignition；　an　airship　within　a　hundred　yards　thereof　would　be

imperilled　seriously；　while　the　other　mines　would　also　be　fired；

communicating　ignition　from　one　to　the　other。　　The　equilibrium

of　the　airship　is　so　delicate　that　it　can　be　readily　upset；　and

taking　into　account　the　facts　that　gas　is　always　exuding　from

the　bag；　and　that　hydrogen　has　a　tendency　to　spread　somewhat　in

the　manner　of　oil　upon　water；　it　is　argued　that　the　gas　would　be

ignited；　and　would　bring　about　the　explosion　of　the　airship。



Another　method　has　even　been　advocated。　　It　is　averred　in

authoritative　circles　that　when　the　aerial　invasion　in　force　of

Great　Britain　is　attempted；　the　Zeppelins　will　advance　under　the

cover　of　clouds。　　Also　that　the　craft　will　make　for　one　

objectiveLondon。　　Doubtless　advantage　will　be　taken　of　clouds；

inasmuch　as　they　will　extend　a　measure　of　protection　to　the　craft；

and　will　probably　enable　the　invading　fleet　to　elude　the　vigilance

of　the　aeroplane　scouts　and　patrols。　　Under　these　circumstances　it

is　suggested　that　balloon…mines　should　be　sent　aloft　and　be

concealed　in　the　clouds。　　It　would　be　impossible　to　detect　the

wires　holding　them　captive；　so　that　the　precise　location　of　the　

lurking　danger　would　not　be　divined　by　the　invader。　　Of　course；

the　chances　are　that　the　invading　airship　would　unconsciously

miss　the　mines；　on　the　other　hand　the　possibilities　are　equally

great　that　it　would　blunder　into　one　of　these　traps　and　be　blown

to　atoms。



An　English　airman　has　recently　suggested　a　means　of　mining

invading　Zeppelins　which　differs　completely　from　the　foregoing

proposals。　　His　idea　is　that　aeroplanes　should　be　equipped　with

small　mines　of　the　contact　type；　charged　with　high　explosives；

and　that　the　latter　should　be　lowered　from　the　aeroplane　and　be

trawled　through　the　atmosphere。　　As　an　illustration　I　will　suppose

that　a　hostile　aircraft　is　sighted　by　a　patrolling　aeroplane。

The　pilot's　companion　in　the　latter　immediately　prepares　his

aerial　mine；　fixing　the　detonator；　and　attaching　the　mine　to　the

wire。　　The　latter　is　then　dropped　overboard；　the　wire　being　paid

out　from　a　winch　until　it　has　descended　to　the　level　of　the

hostile　craft。　　The　airman　now　manoeuvres　in　the　air　circling

about　the　airship；　dragging　his　mine　behind　him；　and　endeavouring

to　throw　it　across　or　to　bring　it　into　contact　with　the　airship

below。　　Naturally　the　latter；　directly　it　observed　the　airman's

object；　would　endeavour　to　elude　the　pursuing　trawling　mine；

either　by　crowding　on　speed　or　by　rising　to　a　greater　altitude。

The　aeroplane；　however；　would　have　the　advantage　both　in　point　of

speed　　and　powers　of　climbing；　while　there　is　no　doubt　that　the

sight　of　the　mine　swinging　in　the　air　would　exert　a　decisive

moral　effect　upon　those　in　the　airship。



Attempts　to　render　the　mine　harmless　by　discharging　it

prematurely　with　the　aid　of　rifle　and　machine…gun　fire　would；　of

course；　be　made　by　the　crew　of　the　airship；　but　the　trawling　mine

would　prove　a　very　difficult　target　to　strike。　　If　such　a　missile

were　used　against　an　airship　of　the　proportions　of　a　Zeppelin　the

mine　would　inevitably　be　trawled　across　the　vessel　sooner　or

later。　　Once　the　airship　had　been　fouled；　the　aviator　would

merely　have　to　drive　ahead；　dragging　the　wire　and　its　charge　

across　the　gas…bag　until　at　last　one　of　the　contact　levers　of　the

mine　was　moved　by　being　dragged　against　some　part　of　the　vessel；

when　the　mine　would　be　exploded。　　In　such　operations　the　aviator

would　run　a　certain　risk；　as　he　would　be　more　or　less　above　the

airship；　and　to　a　certain　degree　within　the　zone　of　the　ultimate

explosion。　　But　there　is　no　doubt　that　he　would　succeed　in　his　

〃fishing〃　exploit　within　a　very　short　time。



This　ingenious　scheme　has　already　been　tested　upon　a　small　scale

and　has　been　found　effective；　the　trawling　bomb　being　drawn

across　its　target　and　fired　by　contact　within　a　few　minutes。　　The

experiment　seems　to　prove　that　it　would　be　simpler　and　more

effectual　to　attack　a　hostile　aircraft　such　as　a　Zeppelin　in　this

manner　than　to　drop　free　bombs　at　random。　　Moreover；　we　cannot

doubt　that　the　sight　of　a　mine　containing　even　ten　or　twelve

pounds　of　high　explosive　dangling　at　the　end　of　a　wire　would

precipitate　a　retreat　on　the　part　of　an　airship　more　speedily

than　any　other　combative　expedient。



The　advocate　of　this　mine…trawling　method；　who　is　a　well…known

aviator；　anticipates　no　d